Sound pressure generator

ABSTRACT

A sound pressure generator includes a tube portion having a flow path extending in a tube axial direction; a rotor having a columnar shape with a column axis extending in a direction intersecting the tube axial direction in the flow path, the rotor configured to generate sound pressure by rotating about the column axis; and a drive unit configured to drive the rotor, wherein a cross-sectional shape of the rotor sectioned across the column axis includes a pointed first tip, a pointed second tip, and a long axis along which the first tip and the second tip are aligned.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application Number 2021-091469 filed on May 31, 2021. The entire contents of the above-identified application are hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to a sound pressure generator.

RELATED ART

In acoustic testing, a sound pressure generator is used as a sound source.

For example, JP H4-129198 A discloses a sound pressure generator, in which a dynamic valve is caused to vibrate with respect to a static valve.

SUMMARY

In acoustic testing, sound pressure with low distortion is desired.

However, in the sound pressure generator disclosed in JP H4-129198 A, the waveform of the sound pressure is sometimes distorted.

It is an object of the present disclosure to provide a sound pressure generator capable of suppressing distortion of sound pressure.

To solve the problem described above, the sound pressure generator according to the present disclosure includes: a tube portion having a flow path extending in a tube axial direction; a rotor having a columnar shape with a column axis extending in a direction intersecting the tube axial direction in the flow path, the rotor configured to generate sound pressure by rotating about the column axis; and a drive unit configured to drive the rotor, wherein a cross-sectional shape of the rotor sectioned across the column axis includes a pointed first tip, a pointed second tip, and a long axis along which the first tip and the second tip are aligned.

According to the sound pressure generator of the present disclosure, distortion of sound pressure can be suppressed.

BRIEF DESCRIPTION OF DRAWINGS

The disclosure will be described with reference to the accompanying drawings, wherein like numbers reference like elements.

FIG. 1 is a schematic view illustrating a state in which a combustor according to a first embodiment of the present disclosure is installed in a gas turbine.

FIG. 2 is a schematic view of test equipment according to the first embodiment of the present disclosure.

FIG. 3 is a front view of a sound pressure generator according to the first embodiment of the present disclosure.

FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3 .

FIG. 5 is a table showing cross-sectional shape patterns of a rotor according to the first embodiment of the present disclosure.

FIG. 6 is a diagram illustrating operation of the sound pressure generator according to the first embodiment of the present disclosure.

FIG. 7 is a graph showing waveforms of sound pressure generated by the sound pressure generator according to the first embodiment of the present disclosure.

FIG. 8 is a graph showing sound pressure levels in harmonic components of sound pressure generated by the sound pressure generator according to the first embodiment of the present disclosure.

FIG. 9 is a cross-sectional view of a rotor according to a comparative example.

FIG. 10 is a graph showing a waveform of sound pressure generated by a sound pressure generator according to a comparative example.

FIG. 11 is a front view of a sound pressure generator according to a second embodiment of the present disclosure.

FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. 11 .

FIG. 13 is a table showing cross-sectional shape patterns of a rotor according to a second embodiment of the present disclosure.

FIG. 14 is a graph showing waveforms of sound pressure generated by the sound pressure generator according to the second embodiment of the present disclosure.

FIG. 15 is a graph illustrating sound pressure levels in harmonic components of sound pressure generated by the sound pressure generator according to the second embodiment of the present disclosure.

FIG. 16 is a schematic view of test equipment according to a modified example of the present disclosure.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will be described with reference to the drawings. The same or equivalent configurations in all drawings are denoted by the same reference signs, and redundant description is omitted.

First Embodiment

A sound pressure generator according to a first embodiment will be described below with reference to FIGS. 1 to 8 .

Overall Configuration of Test Equipment

Test equipment 9 is equipment for testing the acoustic performance of an acoustic device.

For example, the test equipment 9 may be equipment for testing the acoustic performance of an acoustic device 6 provided in a combustor 7 of a gas turbine 8, as illustrated in FIG. 1 .

The acoustic device 6 is a device configured to dampen vibrations generated in the combustor 7 during combustion.

As illustrated in FIG. 2 , the test equipment 9 includes a sound pressure generator 1, a pipe 2 and an air source 3.

For example, the test equipment 9 may be used during element testing of the acoustic device 6.

The element testing of the acoustic device 6 may, for example, be performed solely on the combustor 7 of the acoustic device 6 of the gas turbine 8, as illustrated in FIG. 2 .

The pipe 2 extends from the sound pressure generator 1 into the combustor 7.

For example, the pipe 2 may be a straight pipe extending from the sound pressure generator 1 into the combustor 7.

The air source 3 sends air to the pipe 2 via the sound pressure generator 1.

The air source 3 may, for example, be a compressor or a fan.

The test equipment 9 may further include a test lid 4.

The test lid 4 closes the opening on the sound pressure generator 1 side of the combustor 7 around the pipe 2.

The pipe 2 extends through the test lid 4 into the combustor 7.

Configuration of Sound Pressure Generator

The sound pressure generator 1 is a device configured to generate sound pressure by applying vibration to air.

As illustrated in FIG. 3 , the sound pressure generator 1 includes a tube portion 11, a rotor 12, and a drive unit 13.

For example, the sound pressure generator 1 may be provided between the air source 3 and the pipe 2.

Further, the sound pressure generator 1 may generate sound pressure by applying vibration to air supplied from the air source 3 to the pipe 2.

Configuration of Tube Portion

A flow path A11 in the tube portion 11 extends in a tube axial direction DT.

For example, the tube portion 11 may be in communication with the pipe 2 such that the air supplied from the air source 3 is guided to the pipe 2 via the flow path A11.

For example, the flow path A11 may be a rectangular flow path having a rectangular cross-section perpendicular to the tube axial direction DT.

Further, a column axis CX may extend in the Y direction, and the tube axial direction DT may extend in the Z direction.

Further, the Y direction may be orthogonal to the Z direction, and the 35 direction orthogonal to the Z direction and Y direction may be the X direction.

Configuration of Rotor

The rotor 12 has a columnar shape with the column axis CX extending in a direction intersecting the tube axial direction DT in the flow path A11.

The rotor 12 can generate sound pressure by rotating about the column axis CX.

As illustrated in FIG. 4 , a cross-sectional shape SS of the rotor 12 sectioned across the column axis CX includes a pointed first tip TP1, a pointed second tip TP2, and a long axis LX on which the first tip TP1 and the second tip TP2 are aligned.

For example, the cross-sectional shape SS of the rotor 12 sectioned across the column axis CX may further include a short axis SX that is shorter than the long axis LX and orthogonal to the long axis LX.

Here, the “long axis” is the longest line segment that is uniquely defined between points on the outer periphery of the cross-sectional shape SS.

The “short axis” is the shortest line segment that is uniquely defined between points on the outer periphery of the cross-sectional shape SS.

The first tip TP1 and the second tip TP2 may each have a sharply tapered shape, for example.

The first tip TP1 and the second tip TP2 may each be curved and pointed, for example.

The cross-sectional shape SS of the rotor 12 may, for example, be symmetric about the long axis LX. Further, the cross-sectional shape SS of the rotor 12 may be symmetric about the short axis SX. Here, the cross-sectional shape SS of the rotor 12 may be a section cut perpendicular to the column axis CX.

The cross-sectional shape SS of the rotor 12 may, for example, be long in the direction in which the long axis LX extends.

The cross-sectional area of the flow path A11 having a section orthogonal to the tube axial direction DT and the cross-sectional area of the rotor 12 having a section including the long axis LX and the column axis CX may, for example, be substantially the same.

In the cross-sectional shape SS of the rotor 12, the first tip TP1 and the second tip TP2 may, for example, be connected by a pair of arcs CA.

The cross-sectional shape SS of the rotor 12 may be a shape where two circles each having a diameter greater than the distance between the first tip TP1 and the second tip TP2 and that pass through the first tip TP1 and the second tip TP2 overlap each other. Here, the diameters of the two circles may be equal.

The cross-sectional shape SS of the rotor 12 may be that of a rugby ball that is vertically divided into two equal portions.

The flow path A11 may have a duct diameter DD in a direction orthogonal to the column axis CX, and the diameter of the pair of arcs CA may be larger than the duct diameter DD.

As in Valve D illustrated in FIG. 5 , in the cross-sectional shape SS of the rotor 12, the ratio of the length of the short axis SX to the diameter of each arc CA of the pair of arcs CA may be 40/49.6 or less.

As in Valve E illustrated in FIG. 5 , in the cross-sectional shape SS of the rotor 12, the ratio of the length of the short axis SX to the diameter of each arc CA of the pair of arcs CA may be 30/49.6 or less.

As in Valve F illustrated in FIG. 5 , in the cross-sectional shape SS of the rotor 12, the ratio of the length of the short axis SX to the diameter of each arc CA of the pair of arcs CA may be 20/49.6 or less.

In addition, in FIG. 5 , “Diameter” indicates the diameter of each arc CA of the pair of arcs CA, and “Width” indicates the length of the short axis SX in the cross-sectional shape SS of the rotor 12.

Configuration of Drive Unit

The drive unit 13 rotates the rotor 12.

For example, the drive unit 13 may cause the rotor 12 to rotate about the column axis CX with the column axis CX as the center of rotation.

For example, the drive unit 13 may be a motor.

Operation

Next, the operation of the sound pressure generator 1 of the present embodiment will be described.

As illustrated in FIG. 6 , air AIR is sent from the air source 3 to the flow path A11.

At this time, when the rotor 12 rotates, the first tip TP1 and the second tip TP2 approach and separate from an inner wall 11W of the tube portion 11 defining the flow path A11.

When the first tip TP1 and the second tip TP2 approach the inner wall 11W, the flow path A11 is blocked, and it becomes harder for the air AIR to flow.

On the other hand, when the first tip TP1 and the second tip TP2 separate from the inner wall 11W, the flow path A11 opens widely, and it becomes easier for the air AIR to flow.

Thus, when the rotor 12 rotates, the conductance of the flow path A11 changes periodically.

Therefore, the flow rate of the air AIR varies periodically according to the periodic change in the conductance of the flow path A11, which generates sound pressure.

Actions and Effects

According to the present embodiment, since the cross-sectional shape SS of the rotor 12 is a shape having a pair of pointed tips aligned on the long axis LX, the period for which the rotor 12 blocks the flow path A11 can be shortened.

Thus, the sound pressure generator 1 can suppress distortion of sound pressure.

When sound pressure distortion can be suppressed, the sound pressure generator 1 can generate large sound pressure.

In addition, according to the example of the present embodiment, the cross-sectional shape SS of the rotor 12 is constituted by curved lines to form the shape where the pair of arcs CA are joined.

As a result, harmonics of sound pressure can be suppressed.

Further, according to the example of the present embodiment, as shown in FIG. 7 , the sound pressure generated by the sound pressure generator 1 is a waveform wider than a sine wave in the RG1 region in which the flow path A11 is closed by the rotor 12, and is a waveform close to a sine wave in the RG2 region in which the flow path A11 is opened by the rotor 12.

On the other hand, according to the example of the present embodiment, as shown in FIG. 8 , the harmonic components of sound pressure generated by the sound pressure generator 1 are suppressed.

When, as a comparative example, the rotor has a cylindrical shape with flattened portions on the periphery as illustrated in FIG. 9 , the period for which the rotor blocks the flow path A11 is longer than that of the present embodiment.

Thus, as shown in FIG. 10 , the sound pressure becomes distorted.

In contrast, according to the present embodiment, the period for which the rotor 12 blocks the flow path A11 can be shortened as described above.

As a result, as compared to the comparative example, the sound pressure generator 1 can generate sound pressure having a waveform close to a sine wave and harmonics are suppressed, as shown in FIGS. 7 and 8 .

In addition, according to the example of the present embodiment, since the cross-sectional shape SS of the rotor 12 is symmetrical about the long axis LX, the sound pressure generator 1 can further suppress the distortion of sound pressure.

According to the example of the present embodiment, since the cross-sectional shape SS of the rotor 112 is a shape including the first tip TP1 and the second tip TP2 that are pointed and curved, the integrity of the sound pressure generator 1 is improved.

According to the example of the present embodiment, in the cross-sectional shape SS of the rotor 12, the first tip TP1 and the second tip TP2 are connected by a pair of arcs CA.

Thus, since the cross-sectional shape SS of the rotor 12 is a shape achieved by superimposing two circles, the rotor 12 can have a simple shape.

Accordingly, it is easy to design and fabricate the rotor 12.

Further, according to the example of the present embodiment, the diameter of each arc CA of the pair of arcs CA is larger than that of the duct diameter DD.

Thus, the rotor 12 can be made thin so that expansion of the cross-sectional shape SS to the direction intersecting the long axis LX is reduced.

As a result, the time for which the rotor 12 blocks the flow path A11 can be shortened.

Therefore, the sound pressure generator 1 can further suppress the distortion of sound pressure.

Further, according to the example of the present embodiment, in the cross-sectional shape SS of the rotor 12, the ratio of the length of the short axis SX to the diameter of each arc CA of the pair of arcs CA is 40/49.6 or less.

Furthermore, according to the example of the present embodiment, in the cross-sectional shape SS of the rotor 12, the ratio of the length of the short axis SX to the diameter of each arc CA of the pair of arcs CA is 30/49.6 or less.

Furthermore, according to the example of the present embodiment, in the cross-sectional shape SS of the rotor 12, the ratio of the length of the short axis SX to the diameter of each arc CA of the pair of arcs CA is 20/49.6 or less.

Thus, the rotor 12 can be made thin so that expansion of the cross-sectional shape SS of the rotor 12 to the direction intersecting the short axis SX is reduced.

As a result, the time for which the rotor 12 blocks the flow path A11 can be shortened.

Therefore, the sound pressure generator 1 can further suppress the distortion of sound pressure.

In addition, according to the example of the present embodiment, the cross-sectional area of the flow path A11 having a section orthogonal to the tube axial direction DT and the cross-sectional area of the rotor 12 having a section including the long axis LX and the column axis CX are substantially the same.

Thus, the rotor 12 can temporarily close the flow path A11.

Thus, the sound pressure generator 1 can generate large sound pressure.

Second Embodiment

Next, a second embodiment of the present disclosure will be described with reference to FIGS. 11 to 15 .

The configuration of a sound pressure generator 101 of the present embodiment is similar to the configuration of the sound pressure generator 1 of the first embodiment apart from the points described below.

Configuration of Sound Pressure Generator

As illustrated in FIG. 11 , the sound pressure generator 101 includes the tube portion 11, a rotor 112, and the drive unit 13.

The test equipment 9 may, for example, include the sound pressure 35 generator 101 instead of the sound pressure generator 1.

Configuration of Rotor

The rotor 112 has a columnar shape with a column axis CX extending in a direction intersecting the tube axial direction DT in the flow path A11.

The rotor 112 can generate sound pressure by rotating about the column axis CX.

As illustrated in FIG. 12 , the cross-sectional shape SS of the rotor 112 sectioned across the column axis CX includes a pointed first tip TP1, a pointed second tip TP2, and a long axis LX on which the first tip TP1 and the second tip TP2 are aligned.

The cross-sectional shape SS of the rotor 112 may, for example, further include the short axis SX that is shorter than the long axis LX and orthogonal to the long axis LX.

The first tip TP1 and the second tip TP2 may, for instance, have a sharply tapered shape.

The first tip TP1 and the second tip TP2 may, for example, be curved and pointed.

The cross-sectional shape SS of the rotor 112 may, for example, be symmetric about the long axis LX. Further, the cross-sectional shape SS of the rotor 112 may be symmetric about the short axis SX. Here, the cross-sectional shape SS of the rotor 112 may be a section cut perpendicular to the column axis CX.

The cross-sectional shape SS of the rotor 112 may, for example, be long in the direction in which the long axis LX extends.

The cross-sectional area of the flow path A11 having a section orthogonal to the tube axial direction DT and the cross-sectional area of the rotor 112 having a section including the long axis LX and the column axis CX may, for example, be substantially the same.

In the cross-sectional shape SS of the rotor 112, the first tip TP1 and the second tip TP2 may, for example, be connected by a pair of first arcs CA1 that extend from the first tip TP1, a pair of second arcs CA2 that extend from the second tip TP2, and a pair of parallel straight lines SL extending between the pair of first arcs CA1 and the pair of second arcs CA2.

The diameter of each arc of the pair of first arcs CA1 and the pair of second arcs CA2 may, for example, be larger than the duct diameter DD.

As in Valve G illustrated in FIG. 13 , in the cross-sectional shape SS of the rotor 112, the ratio of the length of the short axis SX to the diameter of each arc of the pair of first arcs CA1 and the pair of second arcs CA2 may be 20/49.6 or less.

As in Valve H illustrated in FIG. 13 , in the cross-sectional shape SS of the rotor 112, the ratio of the length of the short axis SX to the diameter of each arc of the pair of first arcs CA1 and the pair of second arcs CA2 may be 15/49.6 or less.

As in the Valve I illustrated in FIG. 13 , in the cross-sectional shape SS of the rotor 112, the ratio of the length of the short axis SX to the diameter of each arc of the pair of first arcs CA1 and the pair of second arcs CA2 may be 10/49.6 or less.

As in Valve J illustrated in FIG. 13 , in the cross-sectional shape SS of the rotor 112, the ratio of the length of the short axis SX to the diameter of each arc of the pair of first arcs CA1 and the pair of second arcs CA2 may be 5/49.6 or less.

Note that, in FIG. 13 , “Diameter” indicates the diameter of each arc of the pair of first arcs CA1 and the pair of second arcs CA2, and “Width” indicates the length of the short axis SX in the cross-sectional shape SS of the rotor 112.

Actions and Effects

According to the present embodiment, since the cross-sectional shape SS of the rotor 112 is a shape having a pair of pointed tips aligned on the long axis LX, the period for which the rotor 112 blocks the flow path A11 can be shortened.

Thus, the sound pressure generator 101 can suppress distortion of sound pressure.

When the distortion of sound pressure can be suppressed, the sound pressure generator 101 can generate large sound pressure.

In addition, according to the example of the present embodiment, since the cross-sectional shape SS of the rotor 112 is symmetric about the long axis LX, the sound pressure generator 101 can suppress the distortion of sound pressure.

According to the example of the present embodiment, since the cross-sectional shape SS of the rotor 112 is a shape including the first tip TP1 and the second tip TP2 that are pointed and curved, the integrity of the sound pressure generator 101 is improved.

According to the example of the present embodiment, in the cross-sectional shape SS of the rotor 112, the first tip TP1 and the second tip TP2 are connected by the pair of first arcs CA1 that extend from the first tip TP1, the pair of second arcs CA2 that extend from the second tip TP2, and the pair of parallel straight lines SL that extend between the pair of first arcs CA1 and the pair of second arcs CA2.

Thus, the rotor 112 can be made thin so that expansion of the cross-sectional shape SS of the rotor 112 to the short axis SX direction is reduced.

As a result, the period for which the rotor 112 blocks the flow path A11 can be shortened.

Thus, the sound pressure generator 101 can further suppress the distortion of sound pressure.

In addition, according to the example of the present embodiment, the cross-sectional shape SS of the rotor 112 includes a portion constituted by curved lines and a portion constituted by parallel lines to have the shape formed by the pair of first arcs CA1, the pair of second arcs CA2, and the pair of parallel straight lines SL.

Because a portion of the cross-sectional shape SS of the rotor 112 is constituted by curved lines, harmonics of the sound pressure can be suppressed in the same way as in the first embodiment.

Meanwhile, because a portion of the cross-sectional shape SS of the rotor 112 is constituted by parallel lines, the opening area of the flow path A11 can be suddenly and rapidly expanded by the rotor 112 (instantaneous opening). As a result, the sharpness of the waveform of the generated sound pressure can be increased (waveform can be sharpened) and the sound pressure can be brought closer to a sine wave. Note that the rotational position of the rotor 112 at the moment when the opening area of the flow path A11 suddenly expands is a position where the long axis LX is parallel to the inner wall 11W.

Thus, the waveform of the sound pressure generated by the rotor 112 is improved to approach the form of a sine wave.

When the waveform of the sound pressure generated by the rotor 112 can be brought closer to a sine wave, the sound pressure generator 101 can generate large sound pressure.

According to the example of the present embodiment, the sound pressure generator 101 improves the waveform of the generated sound pressure to be closer to a sine wave compared to the sound pressure generator 1 of the first embodiment.

For example, as shown in FIG. 14 , among the waveforms of the sound pressure generated by the sound pressure generator 101, even in the RG3 region in which the rotor 112 closes the flow path A11, the waveform of the sound pressure generated by the sound pressure generator 101 is close to a sine wave.

As a result, the waveform of the sound pressure generated by the sound pressure generator 101 is close to a sine wave over the entire period from when the rotor 112 opens the flow path A11 to when the rotor 112 closes the flow path A11.

For example, as shown in FIG. 15 , of the frequency components of the sound pressure generated by the sound pressure generator 101, the primary component is slightly increased compared to Valve F of the first embodiment. This is believed to be due to the expansion of the pass area upon full opening of the rotor 112 relative to the flow path A11.

Meanwhile, of the frequency components of the sound pressure generated by the sound pressure generator 101, the secondary component can be seen to decrease in line with a decrease in the thickness of the rotor 112.

Of the frequency components of the sound pressure generated by the sound pressure generator 101, the tertiary component and the quaternary component are equivalent to or lower than those of Valve F of the first embodiment.

Thus, the rotor 112, with which the primary component is high and the secondary component low, is effective as a rotor for generating sound pressure having a waveform that is close to a sine wave.

In addition, according to the example of the present embodiment, the diameter of each arc of the pair of first arcs CA1 and the pair of second arcs CA2 is greater than the diameter of the duct diameter DD.

Thus, the rotor 112 can be made thin so that expansion of the cross-sectional shape SS of the rotor 112 to the direction intersecting the long axis LX is reduced.

As a result, the period for which the rotor 112 blocks the flow path A11 can be shortened.

Thus, the sound pressure generator 101 can further suppress the distortion of sound pressure.

In addition, according to the example of the present embodiment, in the cross-sectional shape SS of the rotor 112, the ratio of the length of the short axis SX to the diameter of each arc of the pair of first arcs CA1 and the pair of second arcs CA2 is 20/49.6 or less.

Furthermore, according to the example of the present embodiment, in the cross-sectional shape SS of the rotor 112, the ratio of the length of the short axis SX to the diameter of each arc of the pair of first arcs CA1 and the pair of second arcs CA2 is 15/49.6 or less.

Furthermore, according to the example of the present embodiment, in the cross-sectional shape SS of the rotor 112, the ratio of the length of the short axis SX to the diameter of each arc of the pair of first arcs CA1 and the pair of second arcs CA2 is 10/49.6 or less.

Furthermore, according to the example of the present embodiment, in the cross-sectional shape SS of the rotor 112, the ratio of the length of the short axis SX to the diameter of each arc of the pair of first arcs CA1 and the pair of second arcs CA2 is 5/49.6 or less.

Thus, the rotor 112 can be made thin so that expansion of the cross-sectional shape SS of the rotor 112 to the direction intersecting the short axis SX is reduced.

As a result, the period for which the rotor 112 blocks the flow path A11 can be shortened.

Thus, the sound pressure generator 101 can further suppress the distortion of sound pressure.

In addition, according to the example of the present embodiment, the cross-sectional area of the flow path A11 having a section orthogonal to the tube axial direction DT and the cross-sectional area of the rotor 112 having a section including the long axis LX and the column axis CX are substantially the same.

Thus, the rotor 112 can temporarily close the flow path A11.

Thus, the sound pressure generator 101 can generate large sound pressure.

Modified Example

In the examples of the embodiments described above, the test equipment 9 may include a straight pipe extending from the sound pressure generator 1, 101 into the combustor 7 as the pipe 2, but any pipe may be provided as long as it extends from the sound pressure generator 1, 101 into the combustor 7.

As illustrated in FIG. 16 , test equipment 9 a as a modified example of the test equipment 9 may include a bent pipe that extends into the combustor 7 from the sound pressure generator 1, 101 as a pipe 2 a in place of the pipe 2. In this configuration, the tip of the pipe 2 a that extends into the combustor 7 is bent toward the acoustic device 6.

In the foregoing, embodiments of the present disclosure have been described, but these embodiments are merely illustrative and are not intended to limit the scope of the disclosure. These embodiments may be implemented in various other forms, and various omissions, substitutions, and alterations may be made without departing from the gist of the disclosure. These embodiments and modifications of the embodiments are included in the scope and spirit of the disclosure.

Notes

The sound pressure generator 1, 101 described in the above embodiments is to be understood as follows, for example.

(1) The sound pressure generator 1, 101 according to a first aspect includes: a tube portion 11 having a flow path A11 extending in a tube axial 25 direction DT; a rotor 12, 112 having a columnar shape with a column axis CX extending in a direction intersecting the tube axial direction DT in the flow path A11, the rotor 12, 112 configured to generate sound pressure by rotating about the column axis CX; and a drive unit 13 configured to drive the rotor 12, 112, wherein a cross-sectional shape SS of the rotor 12, 112 sectioned across the column axis CX includes a pointed first tip TP1, a pointed second tip TP2, and a long axis LX along which the first tip TP1 and the second tip TP2 are aligned.

According to the present aspect, since the cross-sectional shape SS of 5 the rotor 12, 112 is a shape having a pair of pointed tips aligned on the long axis LX, the period for which the rotor 12, 112 blocks the flow path A11 can be shortened.

Thus, the sound pressure generator 1, 101 can suppress distortion of sound pressure.

(2) The sound pressure generator 1, 101 according to a second aspect is the sound pressure generator 1, 101 according to (1), in which the cross-sectional shape SS is symmetric with respect to the long axis LX.

According to this aspect, the sound pressure generator 1, 101 can further suppress the distortion of sound pressure.

(3) The sound pressure generator 1, 101 according to a third aspect is the sound pressure generator 1, 101 according to (1) or (2), in which, in the cross-sectional shape SS, the first tip TP1 and the second tip TP2 are curved and pointed.

According to this aspect, the integrity of the sound pressure generator 1, 101 is improved.

(4) The sound pressure generator 1 according to a fourth aspect is the sound pressure generator 1 according to (1) or (2), in which the cross-sectional shape SS is shape in which the first tip TP1 and the second tip TP2 are connected with a pair of arcs CA.

According to this aspect, since the cross-sectional shape SS is a superimposition of two circles, the rotor 12 can be configured with a simple shape.

Therefore, it is easy to design and fabricate the rotor 12.

(5) The sound pressure generator 1 according to a fifth aspect is a sound pressure generator 1 according to (4), in which the flow path A11 has a duct diameter DD in a direction orthogonal to the column axis CX and the diameter of each arc CA of the pair of arcs CA is larger than the duct diameter DD.

According to this aspect, the rotor 12 can be made thin so that expansion of the cross-sectional shape SS to the direction intersecting the long axis LX is reduced.

As a result, the time for which the rotor 12 blocks the flow path A11 can be shortened.

Therefore, the sound pressure generator 1 can further suppress the distortion of sound pressure.

(6) The sound pressure generator 1 according to a sixth aspect is the sound pressure generator 1 according to (4) or (5), in which the cross-sectional shape SS has a short axis SX orthogonal to the long axis LX, and a ratio of the length of the short axis SX to the diameter of each arc CA of the pair of arcs CA 40/49.6 or less.

According to this aspect, the rotor 12 can be made thin so that expansion of the cross-sectional shape SS to the short axis SX is reduced.

As a result, the period for which the rotor 12 blocks the flow path A11 can be shortened.

Therefore, the sound pressure generator 1 can further suppress the distortion of sound pressure.

(7) The sound pressure generator 1 according to a seventh aspect is the sound pressure generator 1 of (6), in which the ratio is 30/49.6 or less.

According to this aspect, the rotor 12 can be made thin so that expansion of the cross-sectional shape SS to the short axis SX is reduced.

As a result, the period for which the rotor 12 blocks the flow path A11 can be shortened.

Therefore, the sound pressure generator 1 can further suppress the distortion of sound pressure.

(8) The sound pressure generator 1 according to an eighth aspect is the sound pressure generator 1 according to (6), in which the ratio is 20/49.6 or less.

According to this aspect, the rotor 12 can be made thin so that expansion of the cross-sectional shape SS to the short axis SX is reduced.

As a result, the period for which the rotor 12 blocks the flow path A11 can be shortened.

Therefore, the sound pressure generator 1 can further suppress the distortion of sound pressure.

(9) The sound pressure generator 101 according to a ninth aspect is the sound pressure generator 101 according to any one of (1) to (3), in which the cross-sectional shape SS is a shape where the first tip TP1 and the second tip TP2 are connected by a pair of first arcs CA1 extending from the first tip TP1 and a pair of second arcs CA2 extending from the second tip TP2 and a pair of parallel straight lines SL extending between the pair of first arcs CA1 and the pair of second arcs CA2.

According to this aspect, the rotor 112 can be made thin so that expansion of the cross-sectional shape SS to the short axis SX is reduced.

As a result, the period for which the rotor 112 blocks the flow path A11 can be shortened.

Therefore, the sound pressure generator 101 can further suppress the distortion of sound pressure.

(10) The sound pressure generator 101 according to a tenth aspect is the sound pressure generator 101 according to (9), in which the flow path A11 has a duct diameter DD in a direction orthogonal to the column axis CX, and the diameter of each arc of the pair of first arcs CA1 and the pair of second arcs CA2 is larger than the duct diameter DD.

According to this aspect, the rotor 112 can be made thin so that expansion of the cross-sectional shape SS of the rotor 112 to the direction intersecting the long axis LX is reduced.

As a result, the period for which the rotor 112 blocks the flow path A11 can be shortened.

Therefore, the sound pressure generator 101 can further suppress the distortion of sound pressure.

(11) The sound pressure generator 101 according to an eleventh aspect is the sound pressure generator 101 according to (9) or (10), in which the cross-sectional shape SS has a short axis SX orthogonal to the long axis LX, and a ratio of the length of the short axis SX to the diameter of each arc of the pair of first arcs CA1 and the pair of second arcs CA2 is 20/49.6 or less.

According to this aspect, the rotor 112 can be made thin so that expansion of the cross-sectional shape SS to the short axis SX is reduced.

As a result, the period for which the rotor 112 blocks the flow path A11 can be shortened.

Therefore, the sound pressure generator 101 can further suppress the distortion of sound pressure.

(12) The sound pressure generator 101 according to a twelfth aspect is a sound pressure generator 101 according to (11), in which the ratio is 15/49.6 or less.

According to this aspect, the rotor 112 can be made thin so that expansion of the cross-sectional shape SS to the short axis SX is reduced.

As a result, the period for which the rotor 112 blocks the flow path A11 can be shortened.

Therefore, the sound pressure generator 101 can further suppress the distortion of sound pressure.

(13) The sound pressure generator 101 according to a thirteenth aspect is the sound pressure generator 101 according to (12), in which the ratio is 10/49.6 or less.

According to this aspect, the rotor 112 can be made thin so that expansion of the cross-sectional shape SS to the short axis SX is reduced.

As a result, the period for which the rotor 112 blocks the flow path A11 can be shortened.

Therefore, the sound pressure generator 101 can further suppress the distortion of sound pressure.

(14) The sound pressure generator 101 according to a fourteenth aspect is the sound pressure generator 101 according to (13), in which the ratio is 5/49.6 or less.

According to this aspect, the rotor 112 can be made thin so that expansion of the cross-sectional shape SS to the short axis SX is reduced.

As a result, the period for which the rotor 112 blocks the flow path A11 can be shortened.

Therefore, the sound pressure generator 101 can further suppress the distortion of sound pressure.

(15) The sound pressure generator 1, 101 according to a fifteenth aspect is the sound pressure generator 1, 101 according to any one of (1) to (14), in which a cross-sectional area of the flow path A11 having a section orthogonal to the tube axial direction DT and a cross-sectional area of the rotor 12, 112 having a section including the long axis LX and the column axis CX are substantially the same.

According to this aspect, the rotor 12, 112 can temporarily close the flow path A11.

Thus, the sound pressure generator 1, 101 can generate large sound pressure.

While preferred embodiments of the invention have been described as above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the invention. The scope of the invention, therefore, is to be determined solely by the following claims. 

1. A sound pressure generator comprising: a tube portion having a flow path extending in a tube axial direction; a rotor having a columnar shape with a column axis extending in a direction intersecting the tube axial direction in the flow path, the rotor configured to generate sound pressure by rotating about the column axis; and a drive unit configured to drive the rotor, wherein a cross-sectional shape of the rotor sectioned across the column axis includes a pointed first tip, a pointed second tip, and a long axis along which the first tip and the second tip are aligned.
 2. The sound pressure generator according to claim 1, wherein the cross-sectional shape is symmetric with respect to the long axis.
 3. The sound pressure generator according to claim 1, wherein, in the cross-sectional shape, the first tip and the second tip are curved and pointed.
 4. The sound pressure generator according to claim 1, wherein the cross-sectional shape is a shape in which the first tip and the second tip are connected by a pair of arcs.
 5. The sound pressure generator according to claim 4, wherein the flow path has a duct diameter in a direction orthogonal to the column axis, and the diameter of each arc of the pair of arcs is larger than the duct diameter.
 6. The sound pressure generator according to claim 4, wherein the cross-sectional shape has a short axis orthogonal to the long axis, and a ratio of the length of the short axis to the diameter of each arc of the pair of arcs is 40/49.6 or less.
 7. The sound pressure generator according to claim 6, wherein the ratio is 30/49.6 or less.
 8. The sound pressure generator according to claim 7, wherein the ratio is 20/49.6 or less.
 9. The sound pressure generator according to claim 1, wherein the cross-sectional shape is a shape where the first tip and the second tip are connected by a pair of first arcs extending from the first tip and a pair of second arcs extending from the second tip and a pair of parallel straight lines extending between the pair of first arcs and the pair of second arcs.
 10. The sound pressure generator according to claim 9, wherein the flow path has a duct diameter in a direction orthogonal to the column axis, and the diameter of each arc of the pair of first arcs and the pair of second arcs is larger than the duct diameter.
 11. The sound pressure generator according to claim 9, wherein the cross-sectional shape has a short axis orthogonal to the long axis, and a ratio of the length of the short axis to the diameter of each arc of the pair of first arcs and the pair of second arcs is 20/49.6 or less.
 12. The sound pressure generator according to claim 11, wherein the ratio is 15/49.6 or less.
 13. The sound pressure generator according to claim 12, wherein the ratio is 10/49.6 or less.
 14. The sound pressure generator according to claim 13, wherein the ratio is 5/49.6 or less.
 15. The sound pressure generator according to claim 1, wherein a cross-sectional area of the flow path having a section orthogonal to the tube axial direction and a cross-sectional area of the rotor having a section including the long axis and the column axis are substantially the same. 